A laser based method was employed to measure and numerically describe the architecture of a corn canopy. Use of the method provides an interception coefficient for classes of vegetation in layers of the canopy viewed in various directions. Architectural data obtained for similar corn canopies but measured by differing methods are comparable to the results obtained using the laser based method. These results provide input data to mathematical models employed in remote sensing for describing the radiation environment in a plant canopy and predicting its reflectance.
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Green and Dead (Chlorotic and Necrotic) Leaf Areas Measured for Each Layer of the Corn Canopya
Height of Layer (m)
Leaf area cm2/layer × plant
Leaf area index
green
dead
total
2.7–3.0
131.6
131.6
0.071
2.4–2.7
615.7
615.7
0.331
2.1–2.4
774.0
774.0
0.417
1.8–2.1
646.7
646.7
0.348
1.5–1.8
893.5
29.0
922.5
0.496
1.2–1.5
766.6
77.8
844.4
0.454
0.9–1.2
332.2
109.5
441.6
0.238
0.3–0.6
337.7
142.8
480.5
0.259
0.0–0.3
111.2
346.1
457.3
0.246
Total leaf area index = 2.860
Measured above soil surface.
Table II
Each Data Point, Representing the First Collision of the Laser Beam with Vegetation and Soil as It Penetrated the Corn Canopya
Type of component
Height of layer (m)
Zenith angle (degrees)
5
15
25
35
45
55
65
75
(Number of hits)
Tassels
2.7–3.0
0
4
1
2
2
3
8
19
2.4–2.7
5
10
11
4
26
15
20
45
2.1–2.4
3
1
1
5
4
3
5
14
1.8–2.1
1
0
0
0
0
0
0
0
1.5–1.8
0
0
1
0
0
0
0
0
1.2–1.5
0
0
0
1
0
0
0
0
0.6–0.9
0
0
0
0
0
1
0
0
Total
9
15
14
12
32
22
33
78
Stems
2.4–2.7
0
0
0
0
1
0
0
0
2.1–2.4
0
1
3
1
3
0
4
3
1.8–2.1
0
1
4
6
S
1
2
2
1.5–1.8
1
2
3
3
2
6
4
0
1.2–1.5
0
1
1
3
2
2
1
0
0.9–1.2
0
0
0
1
2
2
0
0
0.6–0.9
0
1
3
3
3
1
0
0
0.3–0.6
0
0
1
0
2
0
0
0
0.0–0.3
0
1
1
1
1
0
0
0
Total
1
7
16
18
21
12
11
5
Leaves
2.7–3.0
0
1
0
0
1
0
2
1
2.4–2.7
7
4
6
10
14
18
27
40
2.1–2.4
23
32
28
33
42
54
63
46
1.8–2.1
18
25
27
44
35
37
50
22
1.5–1.8
35
37
35
31
17
39
19
6
1.2–1.5
31
30
29
27
27
18
12
2
0.9–1.2
26
22
17
14
10
13
2
1
0.6–0.9
13
4
10
10
7
7
3
1
0.3–0.6
1
3
3
5
3
0
1
0
0.0–0.3
4
2
2
1
3
1
0
0
Total
158
160
157
175
159
187
179
119
Ears
2.1–2.4
0
0
0
0
0
0
1
0
1.5–1.8
0
0
0
2
2
1
0
0
1.2–1.5
4
S
6
0
5
2
3
0
0.9–1.2
1
0
0
1
1
1
2
0
0.6–0.9
0
0
0
0
1
0
0
0
Total
5
5
6
3
9
4
6
0
Soil
Total
84
51
43
29
18
4
0
0
Data points categorized according to the zenith angle of the beam at impact and the height of the layer and type of component hit in the canopy.
Table III
Interception Coefficient of the Plant Canopy is a Function of Canopy Layer and Projection Directiona
Height of layer (m)
Zenith angle (degrees)
5
15
25
35
45
55
65
75
m2 of projected leaf area/m3 canopy
2.7–3.0
0.0
0.068
0.013
0.023
0.030
0.025
0.063
0.090
2.4–2.7
0.159
0.200
0.227
0.168
0.450
0.302
0.340
0.543
2.1–2.4
0.373
0.543
0.480
0.530
0.682
0.669
0.778
0.904
1.8–2.1
0.301
0.488
0.551
0.877
0.755
0.627
1.049
1.056
1.5–1.8
0.659
0.906
0.876
0.870
0.520
1.212
0.947
0.791
1.2–1.5
0.797
1.148
1.123
1.065
1.204
1.052
1.548
0.598
0.9–1.2
0.780
0.978
0.722
0.772
0.694
1.457
0.976
0.598
0.6–0.9
0.453
0.271
0.698
0.842
0.806
1.969
1.953
–
0.3–0.6
0.038
0.174
0.252
0.408
0.483
0.0
–
–
0.0–0.3
0.154
0.184
0.204
0.182
0.473
0.427
–
–
Projected leaf area is the actual leaf area multiplied by the cosine of the angle between the normal to the leaf area and the zenith angle. An interception coefficient could not be calculated for the locations indicated by — because no laser beams at these angles passed through these layers.
Table IV
Probability of Observing One or More Components or the Sky While Looking Upward from a Horizontal Surface In the Corn Canopya
Height of surface (m)
Type of component
Zenith angle (degrees)
5
15
25
35
45
55
(percent)
3.0
Sky
100.0
100.0
100.0
100.0
100.0
100.0
Tassels
0.0
0.0
0.0
0.0
0.0
0.0
Stems
0.0
0.0
0.0
0.0
0.0
0.0
Leaves
0.0
0.0
0.0
0.0
0.0
0.0
Ears
0.0
0.0
0.0
0.0
0.0
0.0
2.4
Sky
95.3
92.0
92.4
93.2
81.6
84.3
Tassels
1.9
5.9
5.1
2.5
11.7
7.8
Stems
0.0
0.0
0.0
0.0
0.4
0.0
Leaves
2.7
2.1
2.6
4.3
6.3
8.0
Ears
0.0
0.0
0.0
0.0
0.0
0.0
1.8
Sky
77.8
66.8
65.7
55.7
44.4
42.8
Tassels
3.2
4.7
4.0
3.1
7.9
5.1
Stems
0.0
0.9
3.3
3.6
4.8
0.7
Leaves
19.0
27.6
27.0
37.5
43.0
51.4
Ears
0.0
0.0
0.0
0.0
0.0
0.0
1.2
Sky
50.2
35.3
33.9
27.4
21.3
13.1
Tassels
2.0
2.5
2.5
2.6
3.8
1.5
Stems
0.4
2.2
3.9
6.4
5.8
7.6
Leaves
44.9
55.9
54.5
62.5
62.1
73.3
Ears
2.4
4.2
5.2
1.0
7.0
4.4
0.6
Sky
34.6
23.9
21.2
15.2
11.3
2.2
Tassels
1.4
1.7
1.6
1.4
2.0
7.4
Stems
0.3
3.1
7.2
10.8
13.7
10.8
Leaves
61.3
68.4
66.8
70.9
65.2
77.7
Ears
2.4
2.8
3.2
1.7
7.7
1.9
0.0
Sky
32.7
21.4
18.2
12.2
7.5
1.7
Tassels
1.3
1.5
1.3
1.2
1.3
5.9
Stems
0.3
4.6
10.2
11.9
19.8
8.6
Leaves
63.5
69.9
67.4
73.3
66.2
82.2
Ears
2.2
2.5
2.8
1.4
5.2
1.5
Height is above the soil surface.
Tables (4)
Table I
Green and Dead (Chlorotic and Necrotic) Leaf Areas Measured for Each Layer of the Corn Canopya
Height of Layer (m)
Leaf area cm2/layer × plant
Leaf area index
green
dead
total
2.7–3.0
131.6
131.6
0.071
2.4–2.7
615.7
615.7
0.331
2.1–2.4
774.0
774.0
0.417
1.8–2.1
646.7
646.7
0.348
1.5–1.8
893.5
29.0
922.5
0.496
1.2–1.5
766.6
77.8
844.4
0.454
0.9–1.2
332.2
109.5
441.6
0.238
0.3–0.6
337.7
142.8
480.5
0.259
0.0–0.3
111.2
346.1
457.3
0.246
Total leaf area index = 2.860
Measured above soil surface.
Table II
Each Data Point, Representing the First Collision of the Laser Beam with Vegetation and Soil as It Penetrated the Corn Canopya
Type of component
Height of layer (m)
Zenith angle (degrees)
5
15
25
35
45
55
65
75
(Number of hits)
Tassels
2.7–3.0
0
4
1
2
2
3
8
19
2.4–2.7
5
10
11
4
26
15
20
45
2.1–2.4
3
1
1
5
4
3
5
14
1.8–2.1
1
0
0
0
0
0
0
0
1.5–1.8
0
0
1
0
0
0
0
0
1.2–1.5
0
0
0
1
0
0
0
0
0.6–0.9
0
0
0
0
0
1
0
0
Total
9
15
14
12
32
22
33
78
Stems
2.4–2.7
0
0
0
0
1
0
0
0
2.1–2.4
0
1
3
1
3
0
4
3
1.8–2.1
0
1
4
6
S
1
2
2
1.5–1.8
1
2
3
3
2
6
4
0
1.2–1.5
0
1
1
3
2
2
1
0
0.9–1.2
0
0
0
1
2
2
0
0
0.6–0.9
0
1
3
3
3
1
0
0
0.3–0.6
0
0
1
0
2
0
0
0
0.0–0.3
0
1
1
1
1
0
0
0
Total
1
7
16
18
21
12
11
5
Leaves
2.7–3.0
0
1
0
0
1
0
2
1
2.4–2.7
7
4
6
10
14
18
27
40
2.1–2.4
23
32
28
33
42
54
63
46
1.8–2.1
18
25
27
44
35
37
50
22
1.5–1.8
35
37
35
31
17
39
19
6
1.2–1.5
31
30
29
27
27
18
12
2
0.9–1.2
26
22
17
14
10
13
2
1
0.6–0.9
13
4
10
10
7
7
3
1
0.3–0.6
1
3
3
5
3
0
1
0
0.0–0.3
4
2
2
1
3
1
0
0
Total
158
160
157
175
159
187
179
119
Ears
2.1–2.4
0
0
0
0
0
0
1
0
1.5–1.8
0
0
0
2
2
1
0
0
1.2–1.5
4
S
6
0
5
2
3
0
0.9–1.2
1
0
0
1
1
1
2
0
0.6–0.9
0
0
0
0
1
0
0
0
Total
5
5
6
3
9
4
6
0
Soil
Total
84
51
43
29
18
4
0
0
Data points categorized according to the zenith angle of the beam at impact and the height of the layer and type of component hit in the canopy.
Table III
Interception Coefficient of the Plant Canopy is a Function of Canopy Layer and Projection Directiona
Height of layer (m)
Zenith angle (degrees)
5
15
25
35
45
55
65
75
m2 of projected leaf area/m3 canopy
2.7–3.0
0.0
0.068
0.013
0.023
0.030
0.025
0.063
0.090
2.4–2.7
0.159
0.200
0.227
0.168
0.450
0.302
0.340
0.543
2.1–2.4
0.373
0.543
0.480
0.530
0.682
0.669
0.778
0.904
1.8–2.1
0.301
0.488
0.551
0.877
0.755
0.627
1.049
1.056
1.5–1.8
0.659
0.906
0.876
0.870
0.520
1.212
0.947
0.791
1.2–1.5
0.797
1.148
1.123
1.065
1.204
1.052
1.548
0.598
0.9–1.2
0.780
0.978
0.722
0.772
0.694
1.457
0.976
0.598
0.6–0.9
0.453
0.271
0.698
0.842
0.806
1.969
1.953
–
0.3–0.6
0.038
0.174
0.252
0.408
0.483
0.0
–
–
0.0–0.3
0.154
0.184
0.204
0.182
0.473
0.427
–
–
Projected leaf area is the actual leaf area multiplied by the cosine of the angle between the normal to the leaf area and the zenith angle. An interception coefficient could not be calculated for the locations indicated by — because no laser beams at these angles passed through these layers.
Table IV
Probability of Observing One or More Components or the Sky While Looking Upward from a Horizontal Surface In the Corn Canopya
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